Tiêu đề item 4 Lung, pleura, trachea and bronchial tree .pdf ✅

1 1 Item 4. Lung, pleura, trachea and bronchial tree Pleura It is a serous membrane lined by mesothelium(simple squamous epithelium) that is present as a closed sac around the lungs. It comprises two layers, outer parietal and inner visceral layer. Pleural cavity It is the potential space between two layers of pleural membranes contain 10-20 ml fluid which is continuously produced by pleura & reabsorbed. 1. It acts as a lubricant so allows easy gliding of pleural layers over each other. 2.It helps maintain negative pressure in pleural space The space becomes apparent if there is accumulation of air (pneumothorax), blood (haemothorax) or pus (empyema). Characteristic features of visceral pleura: ■ It is the inner layer of the two layers of pleura. ■ It is tightly adherent to the outer surface of lung . ■ It also lines the fissures of the lung. ■ It does not cover the hilum of the lung and the area along which pulmonary ligament is attached. ■ It develops from the splanchnopleuric layer of the mesoderm. ■ It is innervated by the autonomic nervous system and is therefore insensitive to pain. ■ It is continuous with the parietal layer at the root of lung.

3 3 structure can allow the lung to protrude upwards, leading to a swelling in the neck, especially during coughing Name the sites where the parietal pleura extends beyond the thoracic cage. Sites where the parietal pleura extends beyond the thoracic cage and is in danger of being injured. ■ Above the medial 1/3rd of the clavicle on both the sides ■ Beyond the right xiphicostal angle ■ Below costovertebral angle on both the sides. Pulmonary ligament : It is the narrow fold of parietal pleura that extend below the root of lung. Functions of pulmonary ligament are: ■ Allows descent of structures of root of lung during inspiration. ■ Provides dead space into which pulmonary vein can expand during increased venous return ( e.g. during exercise).